Thermostatic time cut-out.



J. C. FRANCIS.

THERMOSTATIC TIME CUT-OUT.

APPLICATION FILED JUNE I6. 1915.

Patented July 9, 1918.

ATTys.

UNITED-straws PATENT OFFICE.

JOHN C. FRANCIS, OF BOSTON, MASSACHUSETTS, ASSIGNOR T0 SAMSON ELECTRICCOM= PANY, OF CANTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

I THERMOSTATIC TIME CUT-OUT.

Specification of Letters Patent.

Patented July 9, 191%.

Application filed June 16, 1916. Serial Ho. 104,101

To all whom it may concern.

Be it known that 1, JOHN C. FRANCIS, a citizen of the United States, andresident of Boston, county of Suffolk, State of Massachusetts, haveinvented an Improvement in Thermostatic Time Cut-Guts, of which thefollowing description, in connection with the accompanying drawing, is aspecification, like characters on the drawing representing like parts.

This invention relates to improvements in thermostatic time cut-outsprovided with automatically actuated means which will interrupt thecircuit when the same is operated by an undesirable continuance of anormal current or by a sustained abnormal current.

The object of the present invention is to provide a thermostatic cut-outof simple construction and certainty in operation and which may beeasilyreset to normal position without the necessity of replacement ofably including a parts.

This is accomplished by providing a power actuated switch having meansnormally restraining its action with releasing means actuated by anindependent and lesser source of power said releasing means in turnbeing controlled by a thermostatic device preferbeing controlled.

The various novel features of the invention will be hereinafter morefully described and pointed out in the annexed claims. In the drawings:I Figure l is a front View of a preferred embodying my invention,

Fig. 2 is a side elevation of the same,

Fig. 3 is a vertical sectional view on lines 3-3 Fig. 1 and.

. Fig. at is a diagrammatic view of a fire alarm system equ1pped withthe thermostatic cut-out illustrated in the preceding figures.

The thermostatic time cut-out forming the subject of this invention isillustrated herein as applied to a tire alarm system but it will beunderstood that its use is not limited to lire alarm circuits but thatit may be employed generally to protect electric circuits from asustained abnormal or an abnormally sustained normal heavy current.

-In fire lalarm circuits for buildings, signals, usually in the form ofsingle stroke bells, are distributed throughout the buildheating coil inthe circuit.

ing and are connected-in series in a low re sistance circuit adapted tocarry a heavy current. This signal circuit is normally maintained openbut is adapted to be closed to cause the operation of the signals by arelay circuit containing the usual fire alarm boxes and which carries arelatively small current. In operation, the breaking of the fire alarmbox circuit acts through the relay to close the signal circuit thusactuating the gongs and as each box when pulled is adapted to interruptthe circuit a predetermined number of times the gongs will be struck acorresponding number of times.

In the ordinary operation of such a system the heavy signal actuatingcurrent is intermittent. and maintained only a short time. If, however,the fire alarm box circuit should be accidentally opened or if the relayshould work improperly, the current through the signaling circuit wouldcontinue and intime might heat the coils which actuate the gongs to adangerous degree. The present invention is designed to prevent thepossibility of such accident by cutting out or breakng the main circuitafter the signaling current has continued a predetermined time.

In order to" insure the proper operation of fire alarm circuits it isdesirable that a small current be maintained through the alarm boxes andalso the signaling circuit so that a visual indicator, such as amilammeter, may at all times indicate whether the circuits are in properworking order. For further protection a trouble circuit is oftenutilized to signal the breakage or grounding of the system.

An illustrative system of this character is shown in Fig. 4 in which acurrent supplied by a dynamo 1 or some other suitab e generator iscarried by a main line a hrough 'a cut-out preferably of the typeforming the may be provided for this line adapted to actuate a troublesignal as-will hereinafter more fully appear. The signal branch 0 whichis of low resistance and adapted to carry a heavy signal actuatingcurrent is normally open, being provided with terminals 5, (3, adaptedto be electrically connected by the armature 7 of a relay 8 in asupplemental high resistance fire alarm box circuit (l which mayconveniently be connected at one end to a terminal 10 in .the highresistance circuit I) and at its opposite end by a line at to the commonreturn line a so that current is always maintained in the highresistance branch I) and the alarm box circuit. A mil-ammeter 9 or othermeasuring device placed in said circuits will serve toindicate when thesystem is in operable condition. The circuit 01 contains the usual firealarm boxes 11. each adapted when pulled" to interrupt the current apredetermined number of times.

When, in the operation of the device, an 1 alarm is turned in at one ofthe boxes the breaking of thecurrcnt in the alarm box line at causes therelay 8 to become de'e'nergized, permitting the armature 7 to drop uponthe terminals 5, 6, thus completing the signaling circuit c,'andstriking the gongs S. As soon as the alarm box circuit is againcompleted the armature 7 is withdrawn from the terminals 5, 6 and thehammer of the gongs are restored for the next signal.

As each box is adapted when pulled to 7 break the circuit (1 apredetermined number box at which the alarm is turned in.

' able switch 13 to break the main circuit if the normal heavv signalingcurrent is abnormally sustained or if a sustained normal current isimpressed upon the line.

Vhile the presence of the mil-ammeter in one branch of the signalingcircuit may be suflicient to indicate the condition of the system, atrouble circuit preferably is provided to sound an alarmif the closedcircuit becomes broken or grounded.

As illustrated herein the high resistance circuit 6 is provided with arelay 15 having an armature 16 forming a member of a switch cooperatingwith a terminal 17 in an independent circuit e comprising a battery 18and a continuously ringing bell 19. The circuit 6 is normally maintainedopen, as the presence of a current in the line b energizesthe relay 15and withholds the arma t-ure 16 from contact with the terminal 17,

Releasing or tripping means are provided for disengaging the lockingmeans, said re leasing means including a thermostatic device, preferablyin the form of a heating coil having an inclosed thermostaticallyexpansible melnbcrsubjcct to the action of the heavy signal operatingcurrent.

The releasing or tripping means is pro-' vided with an independentsource of power of less strength than the power means which tends toseparate the switch members but adapted when released to cause thetripping means to impinge sharply upon the locking means to disengagethe latter thus insuring a prompt and sure separation of the switchmembers and the breaking of the circuit. This locking and releasingmeans may be of any suitable character within the scope of my invention.A practical embodiment of the time cut-out aforesaid is illustrated inFigs; 1, 2, and 3 of the accompanying drawings in which the heating oil12 and switch controlled thereby are mounted upon and insulated from asuitable base plate 21.

The line a of the main circuit is connected to an insulated terminal 22which is connected to one end of the heating coil 12, the

other end of said coil being connected to an insulated terminal 25having a contact spring adapted to engage the movable switch member 13.lated and having a spring contact member adapted to engage the movableswitch member 13, is connected to the lines leading through thesignaling and alarm box circuits.

The movable switch member 13 is secured to one arm 28 of a bell cranklever which is pivotally mounted upon a stud 29 extending Anotherterminal, also insufrom the base 21, insulation plates 30, 31

serving. to insulate the switch member 13 from the lever 28. Theopposite arm 32 of the bell crank lever is preferably substantiallyL-shaped and is provided with a stud 33 adapted to be engaged by ashoulder 34 upon 'one arm 35 of an L-shaped detent which is pivotallymounted upon a stud 36 extending from the base 21. The detent ismaintained in contact with'the stud 33 by a spring 33* anchored to thestud 36 and connected to one of the arms of said detent.

' The" bell crank lever is actuated bysuitable power niechanism,preferably a helical spring 37 surrounding the stud 29,one end of saidspring being anchored to the base 21 and the other connected to the arm28 of said lever so thatthe spring normally tends to throw the contactmember 13 out of enagement with the stationary contacts 26, 27. lVhenhowever the stud 33 is engaged by the shoulder 31 of the detent theswitch member 13 is locked in engagementwith the contact members 243, 27and causes the completion of the circuit in the main line through theheating coil 12.

The spring 37 which operates the switch member 13 desirably is ofconsiderable strength to insure the proper actuation of the switch andconsequently forces the stud 33 firmly into engagement with the shoulderof the detent In order to cause the disengagement of the detent aspecial spring actuated tripping mechanism is providedwhich whenreleased will strike the arm.

35 of the detent with sufficient force to insure disengagement from thestud 33, the tripping mechanism being in turn controlled by athermostatic member actuated by the heating coil 12.

as illustrated herein the tripping mechanism comprises a lever 38pivotally mounted upon a stud 39 projecting from the base 21, said lever38 having its arm 4E0 offset and provided with a stud ll located at adis tance from the arm 35 of the detent and adapted upon rotation of thelever upon its pivot to impinge upon said arm- The opposite arm 38* ofthe lever extends over and is adapted to be engaged by athermostatically expansible member within the heating coil.

Independent power means preferably a spring 42 of considerable lesspower than the spring 37 is coiled about the stud 39 and having oneendanchored to the stud 39 and theot-her end engaging the lever 38 tendsnormally to rotate the lever about its pivot 39 so that the stud 41 ofthe trippin mecha nism will strike the arm 35" with consider ablemomentum.

The lever 38 normally supported in the position shown in Fig. 1 againstthe tension of its spring by a thermostatically expansiblc member withinthe heating coil. The thermostatic member preferably is composed of twoelements &3, a l having different co-eiiicients of expansion, such forexam-v ple as brass and steel, whichare secured together and at one endto a stud 45 projecting from the base and at the opposite free end aresecured together by an l -shaped plate d6, which underlies the end ofthe arm 38 of the lever 38 when the thermostatic element is in normal orcool condition. The free end of the thermostatic member normally restsagainst a pin st? projecting from the base plate 21.

qlWhcn, in the operation of-the alarm circuit, an abnormal current ispassed through the main line, or .when the normal heavy sigapredetermined amount of time the heating coil 12 is raised intemperature, causing the expansion of the thermostatic elements 13,

44. These elements having different co-eflicients of expansion expandunequally thus naling current is continued through the line causing adeflection or bending of the ther- .35, thus releasing the detent fromthe stud 33 and permitting the bell crank lever 28 to be rotated uponits pivot under the action of the powerful spring 37 and removing theswitch member 13 from its engagement with the stationary contact members26, 27.

In order to reset the thermostatic time cut-out to normal position thearm 32 of the bell crank lever 28 is provided with a'handle 4:8 and alsowith'an extension 49 projecting over the path of the stud 4E1 on thetripping mechanism so that when the contact member 13 is moved intoengagement with the sta tionary contacts 26 and 27 the trippingmechanism will be rotated against the action of its spring untiltherounded end of the arm 38 rides up beneath the plate 16 of thethermostatic element when the latter has cooled and returned to normalposition, thus again locking the tripping mechanism. A. stop 50 securedto the base may be provided to engage the extension d9 of the arm 32 ofthe bell crank lever 28 and limit its movement.

While the tripping mechanism and the thermostatic member illustratedherein constitute a simple, convenient and preferred embodiment of myinvention, it will be understood that various changes may be made withinthe scope of the following claims and that the embodiment of theinvention herein shown and described is illustrative merely, notrestrictive of the invention defined in the claims.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is;

1. A thermostatic cut-out for an electric circuit comprising switchmembers, power actuating means for giving relative movement to saidmembers, a thermostatic means operable upon a sustained abnormal or anabnormally sustained heavy normal current in said circuit, means forlocking said switch members in conducting position,- areleasing devicenormally out of contact with and un- "*3 influenced by said poweractuating means and adapted to be released by a predetermined movementof said-thermostatic means and independentni'eans for actuating saidment to said members, a thermostatic means operable upon a sustainedabnormal or an abnormally sustained heavy normal current in saidcircuit, means for locking said switch members in' conducting position,a releasing device engaging said thermostatic means and adapted to bereleased by a predetermined movement of said thermostatic means, andindependent means for actuating the said releasing device to release thepower aetuating means thereby to effect relative.

movement of the switch members.

A thermostatic cut-out 't'or an elgctric circuit comprising switchmembers, power actuating means for giving relative movement to'saidmembers, means for holding said switch members in conducting position, athermostatic means operable upon a sustained abnormal or an abnormallysustained heavy normal current in said circuit, an independentspring-actuated releasing device adapted to be held in operativeposition by said thermostatic means and normally uninfiuenced bysaidpower actuating means adapted to be'released by a predetermined movementof said thermostatic means to effeet the release of the said poweractuated means thereby to efi'ect relative opening movement of-saidswitch members.

4. A thermostatic time cut-out for an electric circuit comprising switchmembers, power actuated means for giving relative movement to saidmembers, means for locking said power-actuatedmeans to retain the switchmembers in contacting position, a movable releasing device actuated byan independent mechanism of lesser power and operating when actuated torelease the power actuated means, and thermostatic means controllingsaid releasing device and acting upon a predetermined degree of movementto free said releasing device to actuation by its power.

5. A thermostatic cut-out for an electric circuit comprising switchmembers, spring actuated means for giving relative movement to saidmembers, means for locking said spring actuated means to-retain theswitch members in conducting position, a

movablereleasing device actuated by an independent spring of lesserpower and operating when actuated to release saidspring actuated means,and thermostatic means controlling said releasing device and acting upona predetermined degreeof movement to free said releasing device toactuation by its sprin L A 6. A t ermostatic .time cut-out for anelectric circuit'comprising relatively movable switch members, meansnormally tending to separate said members, detent mechanism adapted toretain sald members In contact,

'tripping means acting when released to strike a blow upon said detentmechanism and thereby to disengage the same, and thermostatic means insaid circuit for releasing said tripping means.

7. A thermostatic time cut-out for an electric circuit comprisingstationary and movable switch members, means normally tending toseparate said members, detent mechanism adapted to retain said membersin contact, independently actuated tripping means for releasing saiddetent mechanism, a heating coil in said circuit, and a thermostatic edto retain said members in contact, tripping means for releasing said'detent mechanism and a heating coil in said circuit having an inclosedcxpansible member for controlling said tripping means, said member beingconstructed of connected elements having different co-efiicients ofexpansion whereby the deflection of said member upon expansion willcause the actuation of the tripping means.

9. A thermostatic time cut-out for electric circuits comprising astationary member and a pivotally mounted cooperating switch member, aspring tending normally to separate said members, a detent ivotallymounted on a stationary'pivot a apted to engage said movable member, aspring actuatedtripping member in cooperative relation to said detent, athermostatic member adapted normally to engage said tripping member andhold the same against the action of its springbut adapted under theinfluence of a.

predetermined amount of heat to release said tripping member and therebycause disengagement of the detent and actuation of the movable member tobreak the circuit.

10. A thermostatic time cut-out for electric circuits comprising astationary ember and a pivotally mounted cooperating -member, a springtending normally to separate said members, a spring actuated detentpivotally mounted on a stationary pivot adapted to engage said movablemember, a

spring actuated tripping member in cooperative relation to said detent,'a thermo static member adapted normally to engage said tripping memberand hold the same against the action of its spring away from said detentvbut adapted under the influence of a predetermined amount of heat torelease said tripping member and thereby cause the same under theinfluence of its mounted cooperating movable switch memher, a springtending normally to swing the movable member away from said stationarymemberpa detent \pivotally mounted on a stationary pivot adapted toengage and retain closed said movablemember, a spring actuated pivotallymounted tripping member in cooperative relation to said detent, aheating coil having an expansible member engaging said tripping memberagainst the action of said spring and adapted under the influence of apredetermined amount of heat to release said tripping member and therebycause disengagement of the detent and the actuation of the movablemember to break the circuit. v

12. A thermostatic time cutout comprising a stationary member and amovable switch member carried by one arm of a bell crank lever, a springacting normally to force said movable member out of contact with saidstationary member, a stud upon the other arm of said bell crank lever, aspring actuated detent mounted upon a stationary pivot and adapted toengage said I stud to lock said contact members in engagement, a springactuated tripping member having a stud normally out of contact with andadapted to strike said detent, a thermostatic member normally holdingsaid tripping mechanism against the action of its spring, and a heatingmeans in said circuit adapted under the influence of apredeterminedamount of current to cause said thermostatic member torelease the tripping member.

13. A thermostatic time cut-out comprising a stationary member and amovable switch member carried by one arm of a bell crank lever, a springacting normally to force said movable member out of contact with saidstationary member, a stud upon the other arm of said bell crank lever, aspring actuated detent mounted upon a stationary pivot and adapted toengage said stud to lock said contact members in engagement, a springactuated tripping member having a stud normally out of contact with andadapted to strike said detent, a thermostatic member normally holdingsaid tripping mechanism against the action of its spring, heating meansin said circuit adapted under the influence of a predetermined amount ofcurrentto cause said thermostatic member to release the tripping memberand means carried by said movable member to cause resetting of saidtripping member when said movable member is moved in reverse direction.

, In testimony whereof, I have signed my name to this specification.

- JOHN C. FRANCIS.

